Vacuum-tube circuits



S. LOEWE VACUUM TUBE CIRCUITS Filed Aug. 29. 1921 W 5 Hal/fry l/VV TOR BY v am), gaunt aunt! ,47'7'0 NEYJ Patented Oct. '2, 1 928.

UNI'TED STATES 1,686,018 PATENT OFFICE.

SIEGMUNID LOEWE, OF BERLIN, GERMANY, ASSIGNOR TO WESTINGHOUSE ELECTRIC & I

IANUFAGTURING COMPANY, A. CORPORATION OF PENNSYLVANIA.

vacuum-TUBE oracurrs.

Ajpplication'filed August 29, 1921, Serial No. 496,404, and in Germany November 13, 1917.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. In, 1313.)

A considerable difficulty arising from the use of vacuum tubes in oscillation genera tors, ,amplifiers, etc. consists in the necessity of the provision of relatively heavy filament batteries. This disadvantage is particularly apparent in transmitters designed for use on aeroplanes, wherein it is necessary to provide filament batteries of sufficient capacity for the longest probable flight.

The present invention has for its object to either entirely eliminate the filament heating battery or to greatly diminish its size. The necessity for carrying the special filament heating battery is due to the fact that relatively large current of low tension is required for heating the filament in contrast to which relatively low current of high tension is required for the anode circuit.

In accordance with this invention a vacu-.

um tube circuit is provided whereby energy is derived from the high tension anode circuit for heating the filament and according ly the filament battery is either entirely dispensed with or greatly diminished in size.

It is, however, generally necessary that some provision be made for initially heating the filament, after which the filament is maintained incandescent as hereinbeforestated. For this purpose there is provided a special current source or a special connection of the anode current source. The time during which the filament is heated in this manner can be either veryshort or can obtain for a certain duration.

The weight of the battery can, therefore, be greatly diminished. When, as is gen erally the case with aeroplane transmitters, the anode current is supplied by means of a generator, so it'is possible, by means of a special winding on the machine, to roduce the heating eflects. Apart from t e fact that the generators are more complicated and heavier, this method has also the disadvantage that thecommutator .ripples are audible. According to the invention, power is taken from the generator for heating the filament only so long as is necessary for starting the oscillation reaction. Then the further heating is accomplished by means of the energy of the produced oscillations. The heating current source can then be out out of the circuit. The advantages consist in the elimination of commutator noise and in fact 1n this case the correspondlng devlces for the initial heating of the filament can be extraordinarily small on account of the short duration of their operation.

With reference to the accompanying drawing which forms a part of this specification,

Fig. 1 shows a vacuum tube circuit in ac cordance with the invention in which the filament heating battery is eliminated and Fig. 2 shows a modified form of the invention wherein a small filament heating battery is employed.

In Fig. 1 reference character 1 indicates a vacuum tube with anode 2, grid 3 and filament 4; 5 is a grid oscillation circuit; 6 an antenna with a tuning coil 7; '8 is the anode circuit which includes coil 9, condenser 10 and generator 11. Preferably this is a direct current generator.

'Whenthe generator is excited it at first charges only the condenser 10. If the condenser 13 is connected into the' circuit by closing switch 12, condenser 10 discharges through the filament 4 until the potential across the condenser 13 is equal to that of the generator 11. By this means a certain amount of current flows into the condenser 13. ,It is possible to regulate this condenser so that just the right amount of current will .flow to bring the filament up to incandes cence. As soon as the filament has become incandescent current flows in the anode circuit and oscillations set in, as will be readily understood. This produces high frequency oscillations in the coil 9, of WhlCh a portion can be taken oil by means of a sliding con-. tact 14, and this amount of current can be regulated so as to be just suflicient to keep the filament glowing.

Instead of taking energy directly from the coil 9, it is of course also possible to provide special coils or oscillation circuits for the generation of the heating current. To prevent overcharging of the filament 4 a suitable resistance can be provided in the filament circuit.

The connection shown can be varied, of

course, in many ways. It is possible, for instance, to use a small heating battery of correspond ng small weight. Furthermore, the

circuit can be improved as indicated in Fig. 2, wherein a very small battery B is utilized for effecting the initial heating of the filament, after which the switch contact 15 can be moved into engagement with contact 17, thereby closin the filament circuit through the coil 18, which is inductively coupled with the coil 9, as shown in Fig. 2.

When the use of an instantaneous connection with regard to the all toosmall conduction of heat or for other reasons is not advisable,ja gradual passage from one energy source to the other can follow, for instance, by means of a resistance in the circuit in such measure that it is put out of the current circuit of the other energy source. With regard to the very limited use of the current source for the initial lighting of the filament, it isalso possible to introduce the whole event through the alteration .of the excitation of the anode tension source. During the time when the eneratorbecomes excited it can be connected or ashort time to the filament,vpreferably through an iron resistance. After the filament is glowing the generator becomes fully excited and at the same time is disconnected from the filament, which then takes further ener -fromtthe produced oscillations. Useful or the indicated purpose are also choke coils which become excited by the current delivered from the main generator. The energy of their field becomes then free through disconnection of the choke coil from its current source, 1

It is then'possible, by means of a special winding, to transfer it in an efiicacious manner upon the filament, which is hereby glowing and is kept glowing in the further course through the oscillations.

I claim.:-

1. A" circuit comprising. an electron dis-- charge device including an anode and a 3. In combination with a thermionic degvice, a plate-circuit including a condenser,.a'* source of energy shunted about said condenser, and means including a condenser effective at the frequency of the currentin the plate circuit for diverting sufficient energy from said plate circuit to the cathode to maintain it thermionically active.

4. In combination with a thermionic device, a plate circuit including a condenser, a

source. of energy shunted about said condenser, the energy from said source being of insufficient frequency to pass said condenser, and means for diverting energy fronn said plate circuit through said condenser for heating the cathode of said thermionic device.

plate circuit for heating the cathode of said thermionic device, a switch controlling said diverting means and preliminary heating means for said cathode controlled by said switch.

7.. In combination with a thermionic device, a plate circuit including a condenser, a source of direct current in shunt to said condenser, means for heating the cathode of said thermionic device, including means 5. In combination with a thermionic defor coupling said cathode to said plate circuit, a second condenser and a switch, whereby, on closing said switch, the current between said condensers will heat said cathode and energy delivered through said coupling will maintain said heating.

8. In an electriccircuit adapted for oscillation at radio frequency, a tube in the circuit for generating radio-frequency oscillations therein, and means in'the circuit for causin said tube to operate, said means normally being dependent upon high-frequency currents generated by the tube for rendering it effective.

.9. In an electric circuit adapted for oscillation at radio' frequency, a tube in the circuit for generating radio-frequency oscillations therein, means in the circuit for causing said tube to operate, said means normally being dependent upon radio-frequency currents generated by the tube itself for rendering it effective, and an exciter circuit for initially renderin said means effective.

In testimon whereof I aflix my signature.

. H .SIEGMUND LOEWE. 

